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AIM: To assess the location, arrangement and possible function of interodontoblastic collagen fibres in association with calcium hydroxide-induced hard tissue bridges by using light and transmission electron microscopy techniques and immunohistochemical staining localization. METHODOLOGY: Prior to the study, an animal use protocol form was reviewed and approved by the Screening Committee for Animal Research of the Tokyo Medical and Dental University. Exposed monkey pulps were capped with a hard-set calcium hydroxide and histopathologically evaluated at 3, 14, 21, 30 and 90 days, using light microscopy with silver staining and transmission electron microscopy to differentiate structural features of interodontoblastic collagen fibres. In addition, an attempt was made to identify and to differentiate between several types of collagen and fibronectin using immunohistochemical localization techniques. RESULTS: At 14 days, interodontoblastic collagen fibres were observed extending from the original dentine, passing through the odontoblasts, and consisted of two portions: a thick fibril and a thin fibril. At 21 days, interodontoblastic collagen fibres were seen penetrating into the predentine and becoming incorporated into the mineralized dentine. At 30 days, interodontoblastic collagen fibres reached the cell process. Although interodontoblastic collagen fibres were no longer observed near the odontoblastoid cells at the area of the newly formed tubular dentine, interodontoblastic collagen fibres were observed embedded within the primary formed dentine bridge. Immunohistochemical staining demonstrated type I collagen and fibronectin within the interodontoblastic collagen fibres. CONCLUSIONS: Interodontoblastic collagen fibres were routinely detected throughout early dentine bridges. Interodontoblastic collagen fibres are thought to be important for initial dentine bridging to induce and support a dentinogenesis framework.

The sequence of factors that mediate pulp inflammation and necrosis are unclear, and controversy surrounds the effects of different pulp capping materials on exposed pulps. Clinicians have few quantitative studies that rank the in vivo pulp capping effects of commonly used restorative materials.

The aim of this study was to evaluate the in vitro durability and fracture modes of the tooth-resin interface following thermal cycling, fatigue load cycling (FLC) and micro-tensile bond strength testing (MTBS).Twenty-four human molars were divided into two groups. In group A, coronal dentin was ground flat with #600-grit SiC paper, Clearfil Linerbond.2V (LB.2V) adhesive was applied and a crown fabricated with Clearfil AP-X resin composite. Samples were loaded in the FLC simulator and thermal cycle device. In group B, Class I cavities were prepared with a diamond bur and the cavity restored with LB.2V/AP-X. Samples were simultaneously subjected to FLC and thermal cycling. After storage of the specimens in water for 1 week, MTBS tests were performed, and fracture modes examined by SEM.For group A, MTBS were approximately 40 MPa with cohesive failures in the bonding resin of all specimens. Neither thermal nor mechanical stressing altered bond strengths on flat dentin surfaces. In group B, MTBS in the unstressed control group was 21 MPa with cohesive failures in the resin. As both thermal and mechanical stresses increased, there was a significant decrease in bond strength (16 MPa, P0.05) and the fractures were seen in the resin-dentin interface and hybrid layer.Surface preparation, C-factor, cavity depth, the dentin substrate and character of the smear layer strongly influence the bond strength values after thermal and fatigue loading. The FLC simulator in combination with MTBS testing provides meaningful in vitro evaluation of dentin bonding durability.

Aim To evaluate the in vitro effect of 2.5% and 5.0% sodium hypochlorite (NaOCl) on human blood. Methodology Each concentration of NaOCl was reacted with human blood for 5 min at volume ratios of 1 : 1, 1 : 6, 1 : 12, each creating changes in colour, pH and temperature. Reaction suspensions were separated by centrifugation, and absorption measurements made for separated bilirubin, Fe, and protein supernatants. Each supernatant was desalted, lyophilized, and treated by SDS polyacrylamide gel electrophoresis (SOS-PAGE). Results Increased ratios and concentrations of NaOCl caused an increase in both pH and temperature. Protein supernatants tended to decompose on SDS-PAGE. Supernatants showed increased decolourisation with 5.0% NaOCl. Concentrations of bilirubin, Ferrum and protein in supernatants decreased with increased NaOCl concentration. NaOCl had an effect on the protein component in blood. Conclusions These data suggest that changes in molecular structure are due to the chemical effects of NaOCl. Protein bands tended to show low molecular weight, suggesting that haemoglobin components effect the oxidation-reduction reaction.

The use of demineralizing agents has been reported to enhance the degree of connective tissue attachment to denuded roots. Of the agents used, tetracycline HCI has received the most attention.The purpose of this study was to evaluate and compare the SEM surface morphology of human root dentin following various concentrations and application times of tetracycline HCl. The surface characteristics were compared and the width of dentin tubule orifices were measured and analyzed. Twelve human teeth were collected and stored in distilled water after soft tissue removal using hand instruments. The apical third of each root was removed and remaining mid-root region was sectioned longitudinally through the root canal following removal of its cementum with a fine diamond bur. A total of 48 dentin specimens were randomly divided into 8 groups for conditioning at different tetracycline HCl concentrations, at 0, 10, 25, 50, 75, 100, 125, and 150 mg/ml. Application times for each group were 1, 3, and 5 minutes. Immediately following treatment procedures, the specimens were rinsed, fixed in GTA-PBF, dehydrated, and prepared for SEM. Each specimen was examined at 2 magnification values, representative fields photographed, and data tested by one-way ANOVA and paired t test statistical analysis.Our results indicate that the use of tetracycline HCl solution between 50 mg/ml and 150 mg/ml showed a statistically significant opening of dentin tubules. All tetracycline HCl groups at 1, 3, and 5 minutes show smear layer removal from the dentin surface.Dentin demineralization is not time dependent at all concentrations of tetracycline HCI.

Vital amputation of the mesio-buccal root of the maxillary fourth premolar (P4) was performed bilaterally in 8 dogs. Histopathologic evaluation of the tooth structure revealed normal pulp in the remaining mesio-buccal, mesio-palatal, and distal roots and crown during a mean follow-up period of 3.5 +/- 1.9 months. Amputation site healing was characterized by a reparative dentin bridge produced by odontoid cells. Tunnel defects were observed in 13 of 16 (81%) dentin bridges. It is concluded that the pulp of a tri-rooted, periodontal disease-free tooth remains viable during a 6-month period following vital root amputation. These results point to the intriguing possibility that this may also occur in humans, however, this needs to be directly tested in man.

This study evaluated the accuracy of the clinical diagnosis of patients with temporomandibular joint dysfunction symptoms compared to a group of asymptomatic volunteers. The clinical examination and history questionnaire used during the evaluation of TMD patients were less accurate evaluating asymptomatic subjects than when combined with computerized joint vibration analysis. “True normal” control subjects were rarely found when these diagnostic modalities were combined in the TMD examination process. Most of the asymptomatic subjects had subclinical signs of TMD. The small sample size is significant, especially since large numbers of subjects appear to be necessary to obtain even small numbers of “True normals.”

Several clinical and laboratory studies have reported data on the nature of tooth wear against restorative materials (that is, amalgam, gold, glass ceramic and various composite resin systems). Several antagonistic substrates are known to cause various in vitro wear rates when placed in opposition to enamel. In this study, the authors evaluated 10 commercially available posterior composite resin systems and a gold alloy control. The findings showed that posterior composite resins containing zirconium silicate or quartz fillers caused greater antagonistic enamel wear than did microfilled or barium silicate-filled composite resins.

Alternatives to calcium hydroxide liners in reducing sensitivity after amalgam placement are considered. Certain clinical and biological studies have reported that prepared dentin and the underlying pulp must be protected with a calcium hydroxide base and liners that supposedly impart biological and structural integrity to tissues. Since the mid-1950s, dentists have relied on a number of calcium hydroxide medicaments for this goal. But recent studies imply that clinicians need to re-evaluate the generous use of certain calcium hydroxide medicaments under restorations.

This investigation evaluated the effects of an experimental light-cured glass ionomer (LCGI) cavity liner and chemically cured Ketac-Bond glass ionomer restorative material on the pulpal tissues of monkeys. Class V cavities were prepared in 71 teeth of three adult Macaca mulatta monkeys at 7- and 35-day intervals. Ketac-Bond or LCGI cavity liners were placed in cavities with the smear layer intact (groups I and II) or with the smear layer removed (groups III and IV) and were restored with composite resin. Tissues were acquired, sectioned at 7 μm, stained for microscopic evaluation, or prepared for SEM evaluation. No statistically significant differences between materials existed at either time interval, regardless of smear layer presence. Histopathologic results demonstrated minimal pulpal reactions for groups I through IV. SEM analysis showed tenacious bonding of the LCGI material to prepared cavity walls, with absence of contraction gap formation. The results indicated excellent pulpal responses to both materials.

Diverse reports have described how various types of adhesive systems cause disastrous pulp necrosis, chronic severe inflammation or failure to stimulate any pulp reactions. This article reports on the effects of five common adhesive systems and how they compare in terms of pulp injury as measured by odontoblast survival or dentin regeneration and reactionary dentin formation. One hundred and thirty Class V pulp, non-exposed cavities were prepared in non-human primate teeth and were restored with five different adhesive systems. After a period of time between 3 and 172 days, the teeth were extracted, fixed, processed and examined histomorphometrically. Bacterial microleakage was detected with McKays stain and inflammation was categorized according to the International Organization for Standardization (ISO) criteria. The number of odontoblasts and the area of reactionary dentin were measured. Pulp reactions of all adhesive systems were generally minimal, although some systems permitted bacterial microleakage in 33% of restorations, and some other systems were associated with pulp inflammation in 22% of restorations. These observations suggest that adhesive systems provide acceptable biocompatibility, however, there is strong potential for improvement.

The purpose of this study was to collect quantitative information about the numbers and dentine bridge secretory activity of odontoblast-like cells following dental pulp exposure.The numbers and secretory activity of odontoblast-like cells were measured histomorphometrically between 7 days and 2 years in 161 pulp-exposed nonhuman primate teeth. The area of dentine bridges and the dimensions of cavity preparations were measured. The density of odontoblast-like cells and subjacent reorganizing tissue cells were measured beneath dentine bridge formation. The presence of operative dentine debris and tunnel defects in bridges was noted. Pulp inflammation was categorized according to ISO standards. Bacteria were detected using McKay's stain.The area of dentine bridges was mediated by the density and secretory activity of odontoblast-like cells over time. The cell density of subjacent reorganizing tissue was found to be strongly associated with that of odontoblast-like cells. Bacterial microleakage was found to impede dentine bridge secretion by odontoblast-like cells.Pulp reparative activity occurs naturally beneath capping materials in the absence of bacterial microleakage. The outcome of pulp-capping treatments could be beneficially influenced by concentrating attention on limiting the width of pulp exposure, minimizing pulp injury by limiting the creation of operative debris and placing materials which prevent bacterial microleakage.

To evaluate the in vitro effect of 2.5% and 5.0% sodium hypochlorite (NaOCl) on human blood.Each concentration of NaOCl was reacted with human blood for 5 min at volume ratios of 1 : 1, 1 : 6, 1 : 12, each creating changes in colour, pH and temperature. Reaction suspensions were separated by centrifugation, and absorption measurements made for separated bilirubin, Fe, and protein supernatants. Each supernatant was desalted, lyophilized, and treated by SDS polyacrylamide gel electrophoresis (SOS-PAGE).Increased ratios and concentrations of NaOCl caused an increase in both pH and temperature. Protein supernatants tended to decompose on SDS-PAGE. Supernatants showed increased decolourisation with 5.0% NaOCl. Concentrations of bilirubin, Ferrum and protein in supernatants decreased with increased NaOCl concentration. NaOCl had an effect on the protein component in blood.These data suggest that changes in molecular structure are due to the chemical effects of NaOCl. Protein bands tended to show low molecular weight, suggesting that haemoglobin components effect the oxidation-reduction reaction.

The aim of this study was to investigate histologically the human pulp response to orthodontic extrusive force applications. In group 1, 20 teeth were extruded with the use of a fixed sectional orthodontic appliance. In group 2, 20 teeth were extruded by means of 1/4-inch 4.5-oz elastics. The test periods were 10 and 40 days. None of the teeth in the groups showed any inflammatory reactions or reparative dentin formation at the test periods. Five teeth from the elastics group and two teeth from the sectional appliance group showed large and numerous pulp stones in the serial sections (17.5% of all cases). Seven teeth from the sectional appliance group and two teeth from the elastics group showed odontoblast aspiration into the dentin tubules (22.5%). The results of the study showed that the extrusive forces applied in this study did not cause significant pathological changes in human pulp tissue.

The purpose of this study was to evaluate the in vivo remineralization of the possible non-resin infiltrated hybridoid layer between the hybrid layer and the subjacent dentin substrate using nanoindentation, energy dispersive x-ray spectroscopy microanalyses (EDS), and scanning electron microscopy (SEM) technologies.Twenty Class V cavities were placed in healthy adult monkey teeth. Each cavity was total etched with 37% phosphoric acid for 60 seconds, rinsed, and air dispersed, and SA-Primer was applied to the collagen layer. Cavities were divided into two groups: In group 1, Protect Liner (low-viscosity resin) and Clearfil AP-X (resin composite) were placed per manufacturer's directions, and no bonding agent was placed on the acid-etched interface. In group 2, Clearfil Photobond (bonding agent) was applied, and Protect Liner and Clearfil AP-X were placed as in group 1. Teeth were observed at 7 days (control) and 6 months by nanoindentation, EDS, and SEM.Six-month data showed an increased nanohardness in areas 5 pm adjacent to the demineralized or partially demineralized dentin interface. Following treatment with a conventional adhesive system on the acid-etched interface (group 2), there were increased nanohardness and calcium EDS measurements in the substrate just below the resin-dentin impregnated layer.Our 6-month in vivo nanoindentation and EDS data demonstrate that the non-resin infiltrated zone becomes remineralized following adhesive resin treatment.

The purpose of this study was to compare the in vitro sealing capacity of five materials, each used as a temporary sealing agent for the walking bleach technique. All teeth received traditional biomechanical root canal instrumentation, after which the walking bleach agent was placed in the pulp chamber space. The occlusal access was sealed with one of five temporary materials: two hydraulic filling materials, a photoactivated resin composite, a zinc oxide-eugenol cement, and a zinc oxide phosphate cement with/without the placement of a piece of rubber sheet that was placed as a barrier to isolate filling material from the bleaching agent. All teeth were stored in a 1% solution of Alcian blue with thermal cycling stress. After 1 wk, they were sectioned longitudinally, and ranked by graded scores of 0 to 3, according to the degree of the dye penetration. Significantly less dye microleakage was observed in the two hydraulic materials than in the photoactivated resin. Both zinc oxide-eugenol and zinc phosphate cements showed a considerable amount of microleakage. There were no significant differences between the groups with and without a rubber sheet. Our data demonstrate that hydraulic filling materials provide the most favorable cavosurface seal when they are firmly packed into the cavity space to prevent microleakage.

Dentistry has experienced exponential growth in the biologic and physiologic knowledge of enamel, dentin, and pulp tissues. In one decade, material development has exceeded clinical testing limits, allowing their arrival to the commercial market without proper validation. This article clarifies the enigma of acid etching; explaining and clarifying the diverse opinions and issues of material toxicity between in vitro and in vivo usage test perspectives. This article also demystifies the biology of pulp healing regarding calcium hydroxide and adhesive systems to promote dentin bridge formation. Lastly, this article provides biologically lucid pulp exposure treatment regimens with agents such as NaOCl, allowing clinicians to increase their long-term clinical success.

The purpose of this study was to observe the seal obtained in human root canals under different in vitro treatment conditions. Root canals of freshly extracted human maxillary incisors received traditional biomechanical preparation and irrigation with 10% NaClO, followed by a final rinse of distilled water. Teeth were divided into four groups. In group 1, each root canal was dried with one paper point. In group 2, each root canal was dried with four paper points. Group 3 was dried with four paper points, followed by a gentle burst of warm air. Group 4 was dried using four paper points, followed by an internal 200 degrees C heat probe. Twenty canals in each group were filled with a gutta-percha cone and a zinc oxide-eugenol sealer, whereas 20 were filled with a glass ionomer sealer. All teeth were immediately immersed in India ink for 1 or 4 wk. The teeth were cleared, and the dye penetration-leakage measured with an accuracy of +/- 0.01 mm. Optimum sealing conditions were observed when the canal was dried with paper points and a 200 degrees C probe. There were no significant differences between 1 and 4 wk immersion. Glass ionomer sealer appeared more susceptible to the wet condition of the root canal walls than zinc oxide-eugenol sealer. An additional 40 teeth were prepared in the same manner as the dye penetration tests to observe the drying conditions of the root canal walls, and the moisture inside the canals was measured to an accuracy of 0.0001 g. The highest degree of internal canal wall dryness was found in group 4.

This study was undertaken to compare the healing response of permanent primate pulps to pulpotomy procedures following hemorrhage control and adhesive hybridization to their response after conventional treatments.Forty-two cavities were placed throughout the dentitions of 4 adult monkeys. In 24 teeth, following mechanical bur exposure and pulpotomy, hemorrhage was controlled with application of 3% sodium hypochlorite. The cavity was rinsed and the enamel-dentin-pulp surface was restored with an adhesive system for 6 and 7 months. Calcium hydroxide, formocresol, and resin-modified glass-ionomer cement were placed as conventional treatments in 18 teeth for 70 days and cavities were sealed with resin-modified glass-ionomer cement. Following perfusion fixation, tissues were demineralized, sectioned, stained, and histologically graded using defined criteria.Of 24 adhesive system pulps, 10 showed no or minimal pulpal response, 1 showed an acute response, 6 showed a chronic response, 2 showed a severe response, and 5 showed compartmentalized zones of localized necrosis. Only 8 adhesive system pulps showed stained bacteria associated with inflamed tissues. Thirteen adhesive system pulps showed dentin bridging directly at the adhesive system interface. Calcium hydroxide-treated specimens showed healing and dentin formation, while resin-modified glass-ionomer cement and formocresol treatments failed to result in any bridging. Apical tissues in all adhesive-treated specimens showed normal pulps and primary odontoblasts along their entire walls.Permanent pulps without periapical radiolucencies may survive pulpotomy, provided that hemorrhage is properly controlled and the pulp-restoration interface is hybridized to exclude all microleakage.

This article provides biological and technological information that strengthens clinicians' understanding of cohesive hybridization and pulp therapy in order to support their routine use of bonding and resin systems. Utilizing cohesive systems, clinicians should experience several advantages over traditional water-soluble base and liner systems. When properly applied, cohesive hybridization of vital dentin prevents immediate postoperative hypersensitivity under all restorations and completely seals the entire tooth-restoration interface, which provides a reduction in recurrent caries.

Objective: The aim of this study was to investigate the human pulp response to Scotchbond Multi Purpose Plus (SMPP) bonding agent in non-exposed Class V cavities. Methods : SMPP was placed in 24 of 40 cavites according to manufacturer's instructions and the cavities were restored with amalgam. The remaining 16 cavities were capped with a calcium hydroxide formulation (Dycal) sealed with zinc-oxide eugenol, and restored with the amalgam. After extraction at 10 and 35 days, the teeth were fixed, sectioned and stained for light microscopy. Results : All Dycal-capped teeth, at both 10 and 35 days, exhibited no pulp inflammation and no demonstrable bacteria. Six cases sealed with SMPP at 10 days showed no pulp inflammation or stained bacterial profiles. The remaining six teeth demonstrated mild to moderate inflammatory pulpal responses and five out of these six cases exhibited stained bacterial profiles. Nine out of 12 teeth showed no inflammatory pulp responses at 35 days, the remaining three cases exhibited mild to moderate pulp inflammation without stained bacteria. Conclusions : None of the teeth sealed with SMPP presented severe inflammatory pulpal reactions histologically. SMPP did not exhibit significant deleterious effects on the human pulp tissue during the test periods.

Background and Objective The aim of study this was to evaluate in vivo the pulpal blood flow rate, pulpal responsiveness, systemic blood pressure, and pulse rate during Nd:YAG laser irradiation of an isolated tooth. Study Design/Materials and Methods Thirteen volunteers from the Tsurumi Dental University faculty participated in this study after giving their consent to the Nd:YAG laser irradiation test protocol. Gingivobuccal areas adjacent to mandibular canines were used for clinical evaluation. Each area was coated with India ink and treated with a Nd:YAG laser for 30 sec at 120-mJ pulses at 10 pulses/sec. Pulpal blood flow was measured by a laser Doppler flowmeter during Nd:YAG laser irradiation of the tooth. All pulp responses were measured by an electric pulp tester before and after Nd:YAG laser irradiation. In addition, the systemic blood pressure and pulse rate were monitored throughout the laser irradiation procedure. Results For all subjects involved in this study, the pulpal blood flow rate increased during laser irradiation. Threshold values of the electric pulp tests increased in six cases and decreased in six cases. One case showed no change. After 1 month, the threshold values for each subject had returned to previously recorded values. Neither systemic blood pressure nor pulse rate was affected during Nd:YAG laser irradiation. Pulpal blood flow was strongly influenced immediately after Nd:YAG laser irradiation, seen as an increase in the flow rate. Conclusion The results of this study suggest that effects of the Nd:YAG laser irradiation are similar to those of low power laser for the improvement of local blood flow. Lasers Surg. Med. 26:270–276, 2000. © 2000 Wiley-Liss, Inc.

The aim of this investigation was to assess the role of the von Korff-like fibers (VKF) during the process of dentin bridging.The monkey pulps, exposed to a hard-set calcium hydroxide, were evaluated at 3, 7, 14, 21, 30, 90, and 180 days.At 21 days, longitudinal and transverse collagen fibrils were organized as lamellar structures in close proximity to and subjacent to the newly formed predentin. VKF bundles were present between newly formed odontoblastoid cells. The VKF were bundles of thin collagen fibrils inserted into the predentin, which consisted of thick collagen fibrils. At 30 days, the exposure site was completely occluded with a new predentin matrix; lamellar structures and VKF were no longer present.The VKF may play a role in the connective tissue attachment to the dentin bridge, early in its formation.

This study evaluated the biocompatibility of a resin-modified glass-ionomer material on monkey pulps.Standardized Class V cavities were prepared in 112 teeth distributed in six healthy adult monkeys. The resin-modified glass-ionomer cement was placed in 24 nonexposed and 36 exposed pulps according to manufacturer's instructions. ZOE was used as a control in nonexposed pulps, while calcium hydroxide was used as a control for exposed pulps. Tissues were collected at 6 to 7, 21 to 27, and 90 to 97 days. After demineralization, the teeth were serially sectioned, stained, and observed by light microscopy.Except for one resin-modified glass-ionomer pulp at 6 days, there were no differences between the responses of nonexposed pulps to resin-modified glass-ionomer specimens and ZOE controls. In exposed pulps, eight of 36 resin-modified glass-ionomer pulps showed various grades of inflammatory response, all associated with stained bacteria. Pulpal healing was similar in both resin-modified glass-ionomer and calcium hydroxide direct-capped exposures. Twenty-two of 26 exposed pulps restored with the resin-modified glass-ionomer cement showed dentin bridge formation at 21 and 97 days.The resin-modified glass-ionomer material exhibited acceptable biologic compatibility in exposed and nonexposed cavities.

To evaluate the histologic response of 332 non-exposed and 127 exposed monkey pulps applying nine adhesive systems.Class V and Class I cavities were used in non-exposed and exposed monkey pulps at the three ISO usage time intervals.There were no histologic differences in pulp responses among the nine adhesive systems used in either Class V and/or Class I cavities when compared to pulp responses of Ca(OH)2 controls at the ISO time intervals. The nine adhesive systems and resin composites are non-toxic to either non-exposed or exposed pulps, being biologically compatible to pulp tissues when placed on mechanical pulp exposures following hemorrhage control with a 2.5% NaOCl and per manufacturers' directions. It is imperative that clinicians understand the biological importance of hemorrhage control as well as the technique sensitivity of hydrophilic primers in order to optimize the efficacy of adhesives for clinical success against microleakage of bacterial factors.

This study evaluated the accuracy of the clinical diagnosis of patients with temporomandibular joint dysfunction symptoms compared to a group of asymptomatic volunteers. The clinical examination and history questionnaire used during the evaluation of TMD patients were less accurate evaluating asymptomatic subjects than when combined with computerized joint vibration analysis. "True normal" control subjects were rarely found when these diagnostic modalities were combined in the TMD examination process. Most of the asymptomatic subjects had subclinical signs of TMD. The small sample size is significant, especially since large numbers of subjects appear to be necessary to obtain even small numbers of "true normals."

Recent studies have demonstrated that acid etching of vital dentin and pulpal tissue does not retard pulpal healing, odontoblastoid cell differentiation, or dentinal bridge formation when the pulp is capped with adhesive resins. The purpose of this study was to evaluate the pulpal response in nonexposed and exposed monkey pulps to treatment with the Clearfil Liner Bond 2 and Clearfil AP-X system.Class V and Class I cavities in nonexposed and exposed pulps were observed at 7 or 8, 27, and 97 days.There were no differences in pulpal inflammation between the Clearfil Liner Bond 2/Clearfil AP-X specimens and calcium hydroxide controls in either Class V or Class I cavities at the various time periods.Clearfil Liner Bond 2 and Clearfil AP-X system is not toxic to either nonexposed or exposed pulpal tissues when placed according to manufacturer's directions.

This study evaluated the histologic responses of two different adhesive systems on the teeth of seven healthy adult monkeys. Class V cavities in 128 teeth were observed at 7,21 to 27, and 90 to 97 days. Statistical data showed no significant differences in pulp inflammation between the Optibond (Kerr), XR-Bond (Kerr), and IRM (Caulk) groups in pulps at the three time intervals. Some odontoblastic disruption and inflammation was seen in pulps restored with XR-Primer at the three time intervals. Pulp healing was similar in teeth treated with both direct-capped Optibond and calcium hydroxide, and there was no significant increase in pulpal inflammation with time. No abscesses or necrotic pulps were seen in any teeth. Optibond and XR-Bond adhesive systems are biologically acceptable in nonhuman primate pulp tissues.

This study evaluated the histologic response of total-etched and nonetched compomer restored cavity preparations. One hundred fifteen class 5 cavity preparations were placed in the teeth of four healthy adult monkeys at 7, 27, and 90 days. A 37% H3PO4 was applied for 10 seconds and rinsed in total-etched preparations. No statistical differences were seen in inflammatory reactions among total-etched or nonetched compomers at 7, 27, and 90 days. There were no statistical differences in inflammatory cell responses among all compomer systems in regard to time intervals. Pulpal responses of compomers were greater than IRM at each time period. Pulp responses were associated with stained bacteria in 32 of 89 compomer teeth. No necrotic pulps were seen in any teeth. Statistical data show a positive correlation (P0.05) between bacterial presence and pulpal inflammation. IRM pulps showed no inflammation or bacterial staining. Compomers are biologically compatible with pulp tissues when bacteria are excluded.

Statement of problem. The wear of human enamel and of the restorative material is often a critical concern when selecting a restorative material for any given clinical restorative treatment. Purpose. This in vitro wear investigation evaluated three ceramic restorative materials and one type III gold (the control) opposing enamel. Material and Methods. The area of enamel lost at specified time intervals, the stylus area lost, and the combined stylus and enamel vertical height lost were evaluated. Results. Enamel wear opposing one type III gold was statistically similar to that of Dicor MGC, which was lower than that of Vita Mark II and IPS Empress, which were also statistically similar in value. Conclusions. The total vertical height lost from the type III gold specimens and opposing enamel was statistically lower than that of Dicor MGC and IPS Empress (α

Class V cavities with mechanical exposures were prepared in 178 teeth of seven monkeys to observe the temporal healing of exposed pulps in direct contact with various dental materials, with or without a biologic seal of zinc-oxide eugenol cement against microleakage. Thirty pulps were direct capped as calcium hydroxide controls. The remaining 148 exposures were direct capped, 41 with silicate, 39 with zinc phosphate, 33 with amalgam, and 35 with an auto-cured composite. Sixty-four were restored to their cavosurface margin with their respective material and 84 were sealed to the covosurface margin with zinc-oxide eugenol cement. Tissues were obtained by perfusion fixation at intervals of 35, 21, 14, 10, 5, and 3 days, and then processed and evaluated. The results of this study demonstrated that exposed dental pulps possess an inherent healing capacity, allowing cell reorganization and dentin bridge formation when adequately sealed with zinc-oxide eugenol cement to prevent bacterial microleakage.

To evaluate the marginal integrity of amalgam restorations in association with four different bonding agents in an in vitro stressing system.Cylindrical cavities were prepared in extracted human molars. The enamel-dentin interface of each cavity was treated with one of four different bonding agents and a non-bonded group. Following treatment with one of the four systems; Amalgambond (AB), Amalgambond Plus (AP) Superbond D-liner II (SD) and Bond-It (BI). Each cavity was then restored with a high-copper spherical amalgam alloy Tytin (TY). Using a load of 75 Newtons (N), a total of 100,000 cycles were applied to each restoration surface. Marginal integrity of each tooth restoration interface was replicated with epoxy and evaluated for gap width with a profilometer and SEM.There were no significant differences in gap width between the loaded and unloaded groups. The non-bonded group (before loading) was statistically different than AB, AP, and SD. In addition, there were no significant differences among the 4-META bonded groups, regardless of the type of bond system, whether loaded or unloaded. The four different bonding agents were significantly different after loading than the non-bonded group. Our SEM and profilometry data demonstrate that the marginal integrity of amalgam alloy restorations is significantly improved by use of bonding systems.

Most microfilled composite resins are relatively resistant to generalized wear; however, they commonly exhibit poor resistance to localized wear because of debonding of prepolymerized particles from the resin matrix. A copolymerized new composite resin, in which the filler particle trimethylolpropane-trimethacrylate is chemically bonded to the resin matrix, is evaluated. Epic-TMPT was subjected to both generalized and localized wear tests that revealed that its wear resistance was higher than that of other composite resin systems. Epic-TMPT in posterior occlusal cavities showed less than 8 microns of wear for each restoration, 1 year after placement. Placement of Epic-TMPT into large anterior abfraction lesions without mechanical retention, with surface etching, and subject to severe traumatic occlusion resulted in 87% retention 1 year after placement. In vivo usage biocompatibility tests demonstrated no pulpal irritation or inflammation when Epic-TMPT was placed on vital dentin of crown preparations with complete enamel removal.

Twenty human permanent teeth were used to study the pulpal response of two calcium hydroxide products, Dycal and Pulpdent Multi-Cal, after partial pulpotomy. Teeth were extracted at 4 months, fixed, and prepared for histologic examination. All 10 teeth treated with Dycal showed complete soft tissue healing and bridge formation. No stained bacteria were seen throughout the serial sections. One tooth treated with Dycal showed acceptable histologic results, dentin deposition in the root canal. Six cases dressed with Pulpdent Multi-Cal showed acceptable histologic results, whereas four teeth showed severe inflammation or necrosis associated with bacterial penetration into the pulp tissue. Clinically, one tooth treated with Pulpdent Multi-Cal showed pulpal pain and was extracted at 90 days. Our data support the thesis that human permanent pulps will promote tissue healing and dentin bridge formation as long as bacterial microleakage is excluded.

This article provides biological and technological information to support routine use of new cohesive bonding systems with definitive restorations. With these systems, clinicians may expect many advantages over the more traditional water soluble base and liner systems. Hybridization of vital dentin will prevent postoperative hypersensitivity under restorations and completely seal the tooth-restoration interface to prevent bacterial infection of the underlying substrate, ultimately reducing recurrent caries underneath the hybridized restoration.

Class V cervical lesions are often observed in older patients during their treatment planning phase, resulting from root caries, toothbrush abrasion, chemical erosion, or to absraction due to unusual tooth flexure. Besides providing a nuisance space as a food trap or plaque buildup, patients also complain of hypersensitivity to air blasts, mechanical stimulation, thermal extremes, or to osmotic fluid shifts. The location of the root lesion in relation to the cemento-enamel junction is of extreme importance. For that reason root lesions limited to the coronal portion of the tooth and completely surrounded by enamel lend themselves to traditional restorative treatment procedures. However, as the root lesion moves apically and its cavosurface circumference is increasingly bound by cementum, clinical treatment becomes much more difficult and in most cases virtually impossible with conventional retentive restorations, and they tend to threaten the root structure and the dental pulp. If these root lesions are left untreated, progressive destruction of root structure occurs and if the causative agents are not removed, the depth of the lesion will threaten the periodontium, dental pulp, and the occlusal integrity of the tooth crown. In addition, cemental lesions are often associated with increased levels of hypersensitivity. Historically, dentistry treated root lesions with direct gold, gold or porcelain inlays, amalgam alloys and crowns, all relying on resistance and retention form. When unrestorable, modification of tooth-brushing techniques along with desensitizing agents were the only desirable treatment due to problems involved with the insertion of a proper restoration. Clinical studies have reported these procedures are often transient, offering no durable restoration of the tooth or elimination of the hypersensitivity.(ABSTRACT TRUNCATED AT 250 WORDS)

A number of studies have reported that acid etching of dentin is toxic to the cells of the odontoblastic layer and dental pulp. Other studies report that pulpal inflammation is a consequence of bacterial microleakage. The purpose of this study was to observe the degree of pulpal healing after pretreatment of vital dentin prior to placement of All-Bond and Scotch-bond 2 composite resin adhesives. Zinc oxide-eugenol cement and an acidic cement were employed as controls. One hundred twelve Class V nonexposed cavity preparations were placed throughout the dentitions of five healthy adult rhesus monkeys and observed at 3, 25, and 80 days. Various dentinal pretreatment procedures were employed. The All-Bond Universal primer system was placed on air-dried vital dentin in 23 cavities and on damp vital dentin in 27 cavities. Scotchbond 2 was placed as per manufacturer's instructions. All treatment procedures, materials, and times were represented in all animals. Placement of silicate cement resulted in the most severe pulpal responses at all time periods. Stained bacterial profiles in the remaining dentin on the axial walls of inflamed control pulps were associated with severe pulpal inflammation. These results indicate that acid etching of vital dentin does not impair pulpal healing in deep Class V cavities.

Adhesive resin systems have become increasingly popular as they have been demonstrated to infiltrate conditioned vital dentin to cohesively hybridize the biologically altered substrates for adhesive bonding. This paper is a review of the biologic and clinical use of Syntac (Ivoclar Vivadent) and Variolink (Ivoclar Vivadent) adhesive systems for cohesive hybridization of vital dentin to prevent patient postoperative hypersensitivity and bacterial microleakage following clinical preparation.

Previous studies have shown degeneration of nerve tissue as well as reorganization by periodontal tissue in dental pulp chambers following intentional vital root transection in Macaca mulatta. The supporting structures of the teeth, as well as the root itself, have not been fully studied following such surgery. The purpose of this study was to observe histopathologic changes in bone and root structure over a 1-year postoperative period. Three adult Macaca mulatta were evaluated for this study. Roots were transected within the apical one third and the areas were surgically closed. Following a postoperative soft diet for 7 days, the monkeys were allowed normal masticatory function. Maxillary and mandibular quadrants were removed following vascular perfusion of the animals at 1, 2, 3, 6, 24, and 52 weeks; quadrants were then demineralized, embedded, sectioned, and stained with Preece's trichrome. Resorption of cementum, dentin, and bone was independently evaluated on microslides for each tooth at consecutive intervals of approximately 70 microns. Resorption was rated as mild, moderate, or severe depending on the number of Howship's lacunae and the dimension of the resorptive area. Severe bone resorption was evident at 1 week, decreasing at 2 weeks, and then progressively decreasing up to 52 weeks. Most active inflammatory root resorption was noted on maxillary and mandibular premolars and molars on first-week specimens. Arrested resorptive areas were present in similar locations in second- and third-week specimens. New cementum was present along the cut surface on specimens from 2 to 52 weeks and within the pulp canal beginning at 2 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)

This study was designed to observe the healing and bridging capacity of mechanically exposed pulps that were capped with silicate or zinc phosphate cements and biologically sealed with zinc oxide-eugenol cement to exclude bacteria. In six monkeys, Class V facial cavities with pulpal exposures were randomly distributed throughout 105 teeth, of which 80 were directly capped, 40 with silicate cement and 40 with zinc phosphate cement. Twenty of each group were filled to the cavosurface margin with the respective cement and 20 were surface sealed to the cavosurface margin with zinc oxide-eugenol cement. The remaining 25 exposures were capped with calcium hydroxide and amalgam as controls. Tissues were obtained by perfusion fixation after intervals of 21, 14, 10, 5 and 3 days. The 25 pulps capped with calcium hydroxide showed cell migration and organization at 5 days and dentinal matrix deposition at 10 days. At 3 and 5 days, all exposures in the experimental groups showed clot resolution. At 10 days, fibroblasts had stratified against the cement interface. At 14 days, pulps in both experimental groups showed new dentinal bridge formation directly adjacent to the acidic cements. The 21-day experimentally capped and sealed pulps presented healing similar to the controls. This study indicates that acidic components of silicate and Zinc phosphate cements are not directly responsible for pulpal inflammation or necrosis. The exposed dental pulp possesses an inherent healing capacity for cell reorganization and dentinal bridge formation when a bacterial seal is provided.

Previous studies have reported revascularization and reorganization of dental pulp chambers with periodontal tissues of monkeys following complete surgical transection through a portion of the apical roots. This study observed 128 teeth in four adult monkeys. Following surgical transection, the tissues were acquired by perfusion fixation, serially sectioned, and stained for cellular detail with hematoxylin and eosin. Collagen tissues were stained with Preece's trichrome and neural tissues with Rowles' silver cyanate for controlled impregnation. At 1 and 2 weeks the coronal tissues showed tissue disruption, necrosis, and degenerating nerves. The 3- and 4-week tissues that had been completely transected showed replacement healing of the pulp tissue with periodontal ligament connective tissue, but no nerves were present. At 6 weeks, no nerves were present in the coronal chambers of those teeth with complete vital transection. The 24-, 36-, and 52-week pulp chambers with complete transection failed to show nerve fibers in their reorganized connective tissues.

The in vitro effect of citric acid application on periodontally involved root surfaces was investigated using scanning electron microscopy. Teeth were selected following specific criteria. The specimens were prepared for observation, and the features of the root surface were studied. The results demonstrated that a 3-minute application of citric acid (pH = 1.0) to the root surface after scaling and root planing demineralized the outer root surface, opened the dentinal tubules, and exposed collagen fibers. Scaling and root planing alone left the surface with a smear layer, scattered islands of cementum, and no collagen fibers or exposed dentinal tubules.

Results of this study showed no correlation between the thickness or amount of reparative dentin deposited and the type of dental restorative material placed at either 5 or 8 weeks in controlled Class V cavity preparations in monkey teeth. Factors such as preparation trauma from the bur, operator hand instrumentation, and microleakage of bacterial toxins played a greater role in the stimulation of reparative dentin than did material irritation or toxicity. Some differences in the thickness of the reparative dentin deposited were noted when teeth were grouped according to the amount of remaining dentin.

A current Med-line search from 1966 to present cited over 344 juried publications employing the term microleakage. Dentistry recognizes microleakage as a multifaceted biological phenomenon. Brännström et al. (1967), Trowbridge (1982), Närhi (1983), and others have reported the sensory component of microleakage as a consequence of hydrodynamic fluid movement within the dentinal tubule complex. This movement of dentinal fluid has been demonstrated to displace nociceptive receptors which stimulate the nerves of the Group A fibers which run and terminate within the odontoblastic layer (see Matthews 1992). Penetration of oral fluids, bacteria and their toxic products within the preparation-material interface following material insertion accounts for the pathological component of microleakage (Browne and Tobias 1986). Continued microleakage of bacterial infiltrates eventually present as an inflammatory process which may initially signal the dentin complex to respond by deposition of a hypermineralized or sclerotic dentin. The pulp-dentin interface will repair with a specialized zone of reparative dentin. An overwhelming carious lesion often results in pulp infection and eventual necrosis. Vital dentin is an extension of the pulp, presenting the first line of defense to the consequences of microleakage. Recent publications have demonstrated that microleakage of dental materials in non-exposed and exposed pulps is a function of controlling bacterial infection. In an exposed mature dental pulp, the mesenchymal tissue permits the reorganization of pulp tissue and regeneration of a new dentin bridge in the presence of a biological seal. New odontoblastoid cells appear to regenerate from deeper pulpoblasts in the presence of various dental materials, apparently without an epithelial stimulating factor (Yamamura 1985). This inherent healing of the dental pulp and regeneration of a new dentin bridge is expressed in the presence of various dental materials, but only in the absence of bacterial infection. Data which evaluates the biological deposition of reparative and dentin bridges as either repair or regeneration are presented as a basis for considering the clinical selections of dental materials. Recent data demonstrate that dentin and pulp healing are ensured when a proper biological seal is provided to control and prevent microleakage.

Microleakage is a biological phenomenon with several implications. The affective component patient hyperalgesia (pain/hypersensitivity) of dentin which is a function of episodic hydrodynan (fluid) movement. The effective component is the disease process which signals the dentin-pulp complex to respond by disposition of sclerotic and/or reparative dentin. Vital dentin is an extension the pulp, presenting the first line of response to the consequences of microleakage. Recent data has demonstrated a correlation between pulp response and material biocompatibility when microleakage is prevented. Dentin-pulp healing is ensured when a proper hermetic seal is provided to control prevent microleakage. A critical evaluation of various clinical procedures is discussed.

The smear layer was first described as a debris layer which is left on all cavity walls following tooth preparation. It is composed of an outer contiguous layer of amorphous instrumentation matrix which covers all cavity walls, and a deeper zone of matrix plugs which obturate the cut tubules. Recent scanning electron microscopic (SEM) studies have characterized the smear layer as mineralized collagen fibers appearing as globules dispersed within an amorphous cutting matrix. Removal of smear plugs increases the outward hydraulic conductance (Lp) of dentinal fluid flow which may lead to dentinal hyperalgesia, bacterial infection and pulp pathosis if left untreated.